In almost all cases concerned with topically applied ophthalmic drugs, no age distinctions are made in the development of dosage regimens. An examination of the factors influencing drug distribution and movement in the eye, however, indicates that the average adult population may not be a suitable basis for determining drug dosages in either pediatrics or geriatrics. This study proposes to quantitate these factors, examine their relative importance, and study the changes which take place as the eye develops and ages with the aim of developing suit-able dosage modifications. A pharmacokinetic approach is proposed which should enable both pediatric and geriatric ocular drug therepy to be placed on a more rational basis.